[HL₂][P(1,2-O₂C₆Cl₄)₃] (L = THF, DMF): Brønsted acid initiators for the polymerization of n-butyl vinyl ether and p-methoxystyrene

The development of solid, weighable Brønsted acids featuring the hexacoordinated phosphorous(V) anion [TRISPHAT]⁻ are reported. H(DMF)₂[1] and H(THF)₂[1] {[1]⁻ = [P(1,2-O₂C₆Cl₄)₃]⁻} were synthesized and fully characterized by ¹H, ³¹P, ¹³C and 2D-NOESY NMR spectroscopy, X-ray crystallography, mass spectrometry and elemental analysis. Both, H(DMF)₂[1] and H(THF)₂[1] are found to be suitable initiators for the polymerization of n-butyl vinyl ether and p-methoxystyrene. Optimal polymerization results for these single-component initiators were generally obtained at −50 °C where high molecular weight polymers were isolated in high yield. ¹H NMR spectroscopic analysis and dynamic light scattering of solutions of the isolated polymers provide evidence for a branched structure which presumably arises from chain transfer.